Powered fastener driver having split gear box

Abstract

A fastener driver includes a housing defining a handle portion, a magazine in which fasteners are held, a nosepiece for receiving fasteners from the magazine, a driver blade movable from a ready position toward a driven position during which a fastener positioned in the nosepiece is driven into a workpiece, a lifting mechanism operable to return the driver blade from the driven position toward the ready position for a subsequent fastener driving operation, and a drivetrain to provide torque to the lifting mechanism. At least a portion of the drivetrain is positioned within and extends through the handle portion of the housing.

What is claimed is: 
     
       1. A fastener driver comprising:
 a housing defining a handle portion; 
 a magazine in which fasteners are held; 
 a nosepiece for receiving fasteners from the magazine; 
 a drive cylinder positioned within the housing; 
 a piston movable within the drive cylinder; 
 a driver blade attached to the piston and movable therewith from a ready position toward a driven position during which a fastener positioned in the nosepiece is driven into a workpiece; 
 a storage chamber cylinder at least partially positioned within the housing in which a pressurized gas is contained, the drive cylinder located within the storage chamber cylinder and in fluid communication with the pressurized gas; 
 a lifting mechanism operable to return the piston and the driver blade from the driven position toward the ready position, thereby compressing the gas in the storage chamber cylinder, for a subsequent fastener driving operation; and 
 a drivetrain to provide torque to the lifting mechanism, 
 wherein at least a portion of the drivetrain is positioned within and extends through the handle portion of the housing. 
 
     
     
       2. The fastener driver of  claim 1 , wherein the drivetrain includes
 an electric motor having a motor output shaft; 
 a first gear box coupled to the motor output shaft to receive torque therefrom; 
 a second gear box having an output shaft coupled to the lifting mechanism to provide torque thereto; and 
 a drive shaft having a first end coupled to the first gear box and a second end coupled to the second gear box for transferring torque from the first gear box to the second gear box, 
 wherein the drive shaft is positioned within and extends through the handle portion of the housing. 
 
     
     
       3. The fastener driver of  claim 2 , wherein the first gearbox includes a first gear case and a multi-stage planetary transmission therein, and wherein the second gearbox includes a second gear case and meshed first and second spur gears therein. 
     
     
       4. The fastener driver of  claim 3 , wherein the spur gears include the same number of teeth. 
     
     
       5. The fastener driver of  claim 3 , wherein the spur gears are offset. 
     
     
       6. The fastener driver of  claim 3 , wherein the second spur gear is coupled for co-rotation with the second end of the drive shaft. 
     
     
       7. A fastener driver comprising:
 a housing defining a handle portion; 
 a magazine in which fasteners are held; 
 a nosepiece for receiving fasteners from the magazine; 
 a driver blade movable from a ready position toward a driven position during which a fastener positioned in the nosepiece is driven into a workpiece; 
 a lifting mechanism operable to return the driver blade from the driven position toward the ready position for a subsequent fastener driving operation; and 
 a drivetrain to provide torque to the lifting mechanism, wherein the drivetrain includes
 an electric motor having a motor output shaft, 
 a first gear box coupled to the motor output shaft to receive torque therefrom, 
 a second gear box having an output shaft coupled to the lifting mechanism to provide torque thereto, and 
 a drive shaft having a first end coupled to the first gear box and a second end coupled to the second gear box for transferring torque from the first gear box to the second gear box, the drive shaft positioned within and extending through the handle portion of the housing, 
 
 wherein the first gearbox includes a first gear case and a multi-stage planetary transmission therein, and the second gearbox includes a second gear case and meshed first and second spur gears therein, the second spur gear being coupled for co-rotation with the second end of the drive shaft, and 
 wherein the drivetrain further includes a single-stage planetary transmission positioned between the second spur gear and the lifting mechanism. 
 
     
     
       8. The fastener driver of  claim 7 , wherein the single-stage planetary transmission includes
 a sun gear coupled for co-rotation with the second spur gear, 
 a carrier shaft rotatably supported by the housing, 
 a ring gear positioned within the second gear case, and 
 a plurality of planet gears rotatably supported upon the carrier shaft and meshed with the ring gear. 
 
     
     
       9. The fastener driver of  claim 8 , wherein the lifting mechanism includes a rotary lifter having pins that engage corresponding teeth of a rack defined on the driver blade, and wherein the rotary lifter is coupled for co-rotation with the carrier shaft. 
     
     
       10. The fastener driver of  claim 9 , further comprising a clutch configured to redirect torque from the motor to the ring gear of the single-stage planetary transmission, causing the ring gear to rotate within the second gear case, in response to a reaction torque applied to the rotary lifter exceeding a predetermined value. 
     
     
       11. The fastener driver of  claim 7 , wherein the meshed first and second spur gears include the same number of teeth. 
     
     
       12. The fastener driver of  claim 7 , wherein the meshed first and second spur gears are offset.